. After reading this thread and a couple of others about the new pen and SP4 keyboard, I just HAD to go to the nearby MS store and try them. Didn't take me more than a minute or two of testing to decide I wanted them. I walked out with new pens for both my S3 and SP3 and a new dark green keyboard for my SP3, which means I had to order the Stickerboy skins for the keyboard.
The pen really does feel nicer in the hand. The writing is more pen- or pencil-like and I love, love, love the eraser. Much easier to use and more natural than trying to remember which darned button is click and which is erase, or having to choose the eraser tool from the roundabout menu.
The original SP3 keyboard was pretty good, but the new one with the island-style keys is even better. I did not get the fingerprint scanner version.